In order to maintain life, form new tissues, and continue an activity for producing milk, meats, eggs, etc., animals must be continuously supplied with sufficient nutrients provided in vitro. Therefore, there have been many attempts to increase characteristics, such as rate of gain, and meat texture, by directly feeding animals amino acids, essential nutrient elements, in addition to an animal feed. However, 60% to 70% of most amino acids digested by a ruminant are autonomously consumed via the digestive process of microorganisms in a ruminant stomach (more specifically, rumen), while some undigested amino acids are merely digested or absorbed in the small intestine. Accordingly, although amino acids are added in feeds for ruminants, an effect such as that in hog-raising and poultry-raising cannot be obtained, and therefore, it is necessary to develop rumen-protected amino acids which bypass the rumen while being capable of being digested by ruminants.
That is, in a case in which amino acids are added in the feeds for ruminants, the amino acids must be absorbed and safely reach the small intestine while avoiding degradation by microorganisms in the rumen. Therefore, the need for an effect of protecting from the rumen or improved novel technology of bypassing the rumen and materials thereof has recently been highlighted.
On the other hand, even though N-acetyl-L-methionine is a material that is known to be used in food additives or animal feeds, the demand for N-acetyl-L-methionine is limited due to its high preparation costs. Additionally, a conventional preparation method thereof uses materials derived from petroleum, which accordingly causes depletion of limited resources and environmental problems (U.S. Pat. No. 7,960,575).
A specific example for the conventional preparation method of N-acetyl-L-methionine refers to a method for producing N-acetyl-L-methionine by acetylation of L-methionine, which is separated from D/L-methionine had prepared by chemical synthesis from petroleum. However, it has some disadvantages in that it takes high costs to separate only L-methionine from D/L-methionine mixtures.
Additionally, the direct fermentation method, in which the L-form can be obtained by over-expressing an acetylating enzyme in methionine-producing strains, has been discovered (U.S. Pat. No. 8,143,031). However, such method has indirectly confirmed that YncA may use acetyl coenzyme A (acetyl-CoA) by DTNB analysis, but has not been confirmed whether N-acetyl-L-methionine is substantially prepared as an enzyme reaction product or a product producing transformants of the gene. Further, the method has a difficulty in commercialization due to its high costs followed by the lowered yield.